Your main idea, introduction paragraph, and thesis statement should clearly come first.
But before you write these elements for your essay, read how to develop a proper outline.
The main idea you mention in thesis statement in the introduction has to be covered through the text.
Decide on an original topic to encourage your audience to read and discuss your idea. It is easy to control the time when you realize WHAT and WHEN to write.
It is similar to the table of contents and should come before introduction and any other paragraph. Every step should involve different argument support in the shape of evidence.
Each sentence of each paragraph should relate to the introduction of your essay. The body must support and refer to the main topic idea as well.
Teachers and professors simply love assigning papers.
They are doing so not to scare you, but to check your knowledge and teach you to manage your time.
It might be helpful to think of the introduction as an inverted pyramid.
In such a pyramid, you begin by presenting a broad introduction to the topic and end by making a more focused point about that topic in your thesis statement.